砂岩成岩过程中的孔隙演化定量模拟———以鄂尔多斯盆地安塞地区长 8 油层组储层为例

孔隙度在埋藏成岩过程中的变化是一个连续的过程，对油气成藏和区域储层评价具有重要意义。 目 前大部分实测孔隙度在深度上都是断续的，针对这一现状，以鄂尔多斯盆地安塞地区长 ₈ 油层组储层砂 岩为例，应用数理统计和数字模拟方法来定量模拟整个埋藏成岩过程中的孔隙演化。 在岩石学特征、成岩 作用特征以及地层埋藏史和成岩史研究的基础上，以现今孔隙度为约束条件，以埋藏深度和埋藏时间为 变量，将研究区长 ₈ 油层组孔隙演化进程分为孔隙度减小和孔隙度增大 2 个过程，并分别建立了相应的 从埋藏初始至今的孔隙演化定量模型。 结果表明，机械压实作用阶段的孔隙度减小过程是以埋藏深度为 自变量的连续函数；压实胶结作用阶段的孔隙度减小过程、增孔窗口阶段（65～100 ℃）及次生孔隙度保持 阶段均是埋藏深度和埋藏时间的连续函数。 因此，分段模型叠加得到的总孔隙演化模型为一个四段式函 数。 利用研究区实际地质资料对孔隙演化定量模型进行的实例验证表明，该模型在砂岩孔隙演化模拟方 面有较好的应用效果。

Quantitative simulation on pore evolution in diagenetic process of sandstone: A case study from Chang 8 oil reservoir set in Ansai area,Ordos Basin

The change of porosity in buried diagenetic process is a continuous process, which has important significance to hydrocarbon accumulation and regional reservoir evaluation. By using mathematical statistics and numerical simulation method, this paper carried out quantitative simulation of pore evolution during the whole burial diagenetic process of Chang ₈ oil reservoir set in Ansai area. Based on analysis of petrologic characteristics, diagenetic features, burial history and diagenesis history, with current porosity as boundary constraint conditions, geological time and burial depth as variables, the whole pore evolution of Chang ₈ oil reservoir set from initial burial until nowadays was divided into two independent processes: porosity decrease and porosity increase, for which two mathematical models were established respectively. The quantitative simulation result indicates that the porosity decrease model of mechanical compaction stage is a continuous function with burial depth as the independent variable, while that of ompactioncementation stages and porosity increase model under temperature window conditions and secondary porosity preservation （65～100 ℃） are continuous functions with geological time and burial depth as the variables. The whole pore evolution quantitative simulation built from the superimposition of porosity decrease and increase is a piecewise function with four sections. Finally, through the exemplification, it is verified that this approach works well in sandstone pore evolution simulation.